Fusible multi-contact electrical connector



Aug. 25, 1964 THORNE 3,146,326

FUSIBLE MULTI-CONTACT ELECTRICAL CONNECTOR Filed May 28, 1962 W: 5% MM1% 4mm x United States Patent 3,146,326 FUSIBLE MULTI-CONTACT ELECTRICALCONNECTOR Beryl Freda Thorne, Beckenham, Kent, England, assignor toSubmarine Cables Limited, London, England, a

company incorporated of the United Kingdom Filed May 28, 1962, Ser. No.198,006 Claims priority, application Great Britain June 2, 1961 12Claims. (Cl. 200-123) This invention relates to electrical connectors ofthe kind in which permanent electrical connection between at least twospaced electrodes is establishable by the application of heat to fusiblematerial disposed on surfaces of said electrodes.

Such a connector may be utilised in a submarine cable repeater amplifierfor the purpose of establishing altered and permanent circuitconnections within the amplifier consequent on failure of a componenttherein and for isolating that part of the amplifier circuit containingthe defective component. When installed in a submarine cable repeateramplifier which is laid possibly on an uneven sea bed it is particularlyimportant that the connector should operate reliably in any attitude inwhich the repeater may have come to rest.

It is an object of the present invention to provide a connector of thetype set forth which will in operation, establish the requiredconnections between electrodes, irrespective of the attitude of theconnector.

The single figure of the drawing illustrates by Way of example only, anelectrical connector according to the invention.

- Referring to the drawing, an electrical connector comprises acylindrical tubular centre electrode 1 and cylind'rical cup shaped andelectrodes 2 and 3, the electrodes 1, 2 and 3 being axially aligned uponan electrically conductive electrode support member constituted by a rod4. The centre electrode 1 is attached to the rod 4, for example, bybrazing to ensure good electrical contact therewith and is provided witha dividing means, as shown a radial, circumferential flange 12 about itsmid portion,

the diameter of the flange 12 being equal to that of the end electrodes2 and 3. V

The end electrodes 2 and 3 are radially spaced from the rod 4, and areeach arranged to overlap the adjacent extremity of the centre electrode1, the external diameter of the centre electrode 1 (except for theflange 12), being less than the internal diameter of the end electrodes2 and 3. The rod 4 is insulated from the end electrodes 2 and 3 bysleeves 5 of insulating material.

The electrodes 1, 2 and 3 are enclosed within and thermally connected toa tubular heating resistor 6, each end of which abuts against a flangeformed around the circumference of the outer end of each end electrode 2and 3, which flanges in conjunction with clamping nuts 7 and insulatingwashers 8 serve to determine the axial spacing of the end electrodes 2and 3, relative to the centre electrode 1. The spaced electrodes whenfitted within the resistor 6 thus define two closed chambers isolatedfrom each other by the circumferential flange 12 on the centreelectrode 1. In the illustrative embodiment, the end electrodes 2 and 3are connected to terminal tags 13 and 14 respectively.

The internal surfaces 9 of the end electrodes 2 and 3 and externalsurfaces 10 of the centre electrode 1, each have disposed thereon alayer 11 of a eutectic alloy solder. The thickness of the layers 11 isso arranged as to leave an air gap between the layers of solder onadjacent electrodes, sufiicient to prevent electrical continuitytherebetween. At the same time the thickness is sufiicient to ensurethat, on melting of the solder, a conductive bridge ICC is formed ineach chamber between centre electrode 1 and the adjacent end electrodes2 and 3.

The solder is heated by the resistor 6 which is connected throughconductors 6a and 6b and terminal tags 13 and 14 respectively to asource of heating current (not shown). Conveniently the normal value ofthe current is arranged to be such as to cause generation ofinsufiicient heat in the resistor 6 to cause melting of the solder.Should the current exceed this normal value, the increased heatgenerated by the resistor 6 melts the solder which then flows into theintervening space in each chamber between the adjacent electrodes 1, 2and 3 and forms conductive bridges therebetween. Subsequently if thecurrent returns to the normal value, the solder solidifies and formspermanent connections.

The electrical connector of the present invention has particular utilityin submerged cable repeater equipment; for example, the heating resistor6 may be connected in parallel with the repeater amplifier valve heatingcurrent, the current through the heating resistor 6 being insufficientunder normal conditions to cause melting of the solder.

If the current through the resistor 6 increases consequent for example,on a valve failure causing an open circuit, the solder is melted andbridges the electrodes 1, 2 and 3 which, by connection within anappropriate circuit, can be arranged to short circuit that half of theamplifier which is defective and also to prevent further flow of currentthrough the resistor 6, thus permitting the solder to cool and solidifyto form permanent connections between the electrodes.

Preferably the layers 11 of eutectic alloy solder are ap 'plied to theelectrodes 1, 2 and 3 under conditions of vacuum in a closed vesselthereby avoiding the formation of air pockets within the solder layers11.

What I claim is: i i

1. An electrical connector of the type in which permanent electricalcontinuity is established between spaced electrodes in response to theapplication of heat to fusible material; said connector comprising acentre electrode, two end electrodes; means supporting said centre andend electrodes in spaced relationship from each other and from saidcentre electrode so as to define a cavity; means insulating said endelectrodes from said centre electrode;

fusible material disposed on said electrodes; resistance means thermallyconnected to said electrodes for heating said fusible material; andmeans for subdividing said cavity into two chambers, each containingfusible material, and preventing flow of fusible material from onechamber to the other; the spacing of said electrodes being such as toensure the establishment of electrical continuity between each of thesaid end electrodes and said centre electrode on melting of said fusiblematerial, irrespective of the attitude of the connector.

2. A connector as claimed in claim 1 in which the centre electrode istelescopically fitted within the end electrodes.

3. A connector as claimed in claim 1 in which each of the electrodes iscylindrical, the fusible material being disposed over at least an innersurface of the end electrodes and over spaced external surfaces of thecentre electrode.

4. A connector as claimed in claim 1 in which said means supporting saidcentre and end electrodes comprises a conductive rod, and in which thecentre electrode is attached to the conductive rod and is in electricalcontact therewith.

5. An electrical connector of the type in which permanent electricalcontinuity is established between spaced electrodes in response to theapplication of heat to fusible material; said connector comprising acentre electrode,

two end electrodes; means supporting said centre and end electrodes inspaced relationship from each other and from said centre electrode so asto define a cavity; means insulating said end electrodes'from saidcentre electrode; fusible material disposed on said electrodes;resistance means comprising a tubular heating resistor within which saidelectrodes are fitted for heating said fusible ma terial; and means forsubdividing said cavity into two chambers, each containing fusiblematerial, and preventing flow of fusible material from one chamber tothe other; the spacing of said electrodes being such as to ensure theestablishment of electrical continuity between each of the said endelectrodes and said centre electrode on melting of said fusiblematerial, irrespective of the attitude of the connector.

6. A connector as claimed in claim 1 in which the centre electrodecomprises a tube, each of the end electrodes being formed by acylindrical cup, the open end of which faces the centre electrode andwherein said dividing means comprises a radial flange disposed about thecentre part of the tube.

7. A connector as claimed in claim 6 in which the external diameter ofthe end electrodes equals that of the radial flange of the centreelectrode, the diameter of the tube of the centre electrode being lessthan the internal diameter of the end electrodes.

8. A connector as claimed in claim 1 in which the fusible material is aeutectic alloy solder.

9. An electrical connector comprising a centre and two axially spacedend electrodes, an electrode support member upon which said electrodesare'asscmbled, means carried by the centre electrode dividing the spacewithin the connector into two parts, means insulating each of the endelectrodes from the support member and from the centre electrode,fusible material disposed over the surfaces of the electrodes withineach part, said electrodes being fitted within a tubular resistorconnectable to a source of heating current, said resistor beingeffective in response to a predetermined value of the heating current tocause melting of the fusible material in each part of said connector,and the electrodes being so spaced as to ensure the establishment ofelectrical continuity between said electrodes, on melting of the fusiblematerial, irrespective of the attitude of the connector.

10. An electrical connector of the kind in which permanent electricalconnection between spaced electrodes is established by application ofheat to melt fusible material disposed thereon, comprising a centresupport member of conductive material, two electrodes spaced axiallyfrom one another and radially from said support member, said electrodesbeing insulated from said support member, means carried by said supportmember for dividing the connector into tWo parts, layers of fusiblematerial disposed on said electrodes and the support member, and aresistance element thermally connected to the electrodes and arranged togenerate suflicient heat in response to a heating current exceeding apredetermined value to melt the fusible material, said fusible materialbeing so disposed relatively to said electrodes that irrespective of theattitude of the connector, electrical connection between the supportmember and the electrodes will be established when the fusible materialis melted.

11. An electrical connector of the type in which permanent electricalcontinuity is established between spaced electrodes in response to theapplication of heat to fusible material; said connector comprising atubular insulating cover and disposed within said cover an axial rod,and mounted on said rod a cylindrical, central electrode and a pair ofaxially spaced tubular end electrodes, means insulating said endelectrodes from said rod; fusible material disposed on the exterior ofthe central electrode and on the interiors of the tubular endelectrodes, said end and central electrodes, together with part at leastof the fusible material disposed thereon, being radially spaced todefine a cavity and said central electrode having a radial flangeconstituting a partition subdividing said cavity into two fusiblematerial containing chambers and preventing flow of said material, whenfused, from one chamber into the other; and the dimensions of saidchambers and the quantities of fusible material therein contained beingsuch as to ensure electrical continuity between each of the endelectrodes and the central electrode on fusing of the fusible material,irrespective of the attitude of the connector; and means responsive toopen-circuiting of a shunt across the end electrodes for heating saidfusible material to melting point.

12. A connector as claimed in claim 11, in which said last mentionedmeans is a resistor interconnecting said end electrodes. 8

References Cited in the file of this patent UNITED STATES PATENTSMcEachron et a1 Aug. 21, 1934

1. AN ELECTRICAL CONNECTOR OF THE TYPE IN WHICH PERMANENT ELECTRICALCONTINUITY IS ESTABLISHED BETWEEN SPACED ELECTRODES IN RESPONSE TO THEAPPLICATION OF HEAT TO FUSIBLE MATERIAL; SAID CONNECTOR COMPRISING ACENTRE ELECTRODE, TWO END ELECTRODES; MEANS SUPPORTING SAID CENTRE ANDEND ELECTRODES IN SPACED RELATIONSHIP FROM EACH OTHER AND FROM SAIDCENTRE ELECTRODE SO AS TO DEFINE A CAVITY; MEANS INSULATING SAID ENDELECTRODES FROM SAID CENTRE ELECTRODE; FUSIBLE MATERIAL DISPOSED ON SAIDELECTRODES; RESISTANCE MEANS THERMALLY CONNECTED TO SAID ELECTRODES FORHEATING SAID FUSIBLE MATERIAL; AND MEANS FOR SUBDIVIDING SAID CAVITYINTO TWO CHAMBERS, EACH CONTAINING FUSIBLE MATERIAL, AND PREVENTING FLOWOF FUSIBLE MATERIAL FROM ONE CHAMBER OF THE OTHER; THE SPACING OF SAIDELECTRODES BEING